Running Rough! O2 Sensor? Help Anyone!

I have a 98 4.3L s10. When I run upwards of 60Km/hr + my stuck feels like it vibrates, and generally isint running smoothly, and my engine light recently came on. I have been told that it may be my 02 sensor. I already changed the plugs, wires, rotor, and not long ago had the catalytic coverter replaced. Does anyone have any suggestions that could help me out?

Thank You in Advance